Master-slave systems have been proposed for use in telerobotics to perform tasks on remote or dangerous locations, such as in a nuclear-, (deep) sea-, or space environment. Another important application scenario lies in the medical field, where hand-controlled master devices are used in remote or proximity medical surgery, e.g. as a hand interface for minimal invasive surgery coupled with surgery robots.
Several solutions have been proposed in the art. The devices shown in Nakagawara et al. (S. Nakagawara, H. Kajimoto, N. Kawakami, S. Tachi, and I. Kawabuchi, “An encounter-type multi-fingered master hand using circuitous joints,” in IEEE Int. Conf. Robotics and Automation ICRA, April 2005, pp. 2667-2672), or Fontana et al. (M. Fontana, A. Dettori, F. Salsedo, and M. Bergamasco, “Mechanical design of a novel hand exoskeleton for accurate force displaying,” in Proc. IEEE Int. Conf. Robotics and Automation ICRA. Piscataway, N.J., USA: IEEE Press, 2009, pp. 2599-2604) 2) can be placed directly on the user's fingers and hand. However, such master devices do not only cover the hand, but also the wrist. According to the solution proposed in Hasegawa et al. (Y. Hasegawa, Y. Mikami, K. Watanabe, and Y. Sankai, “Five-fingered assistive hand with mechanical compliance of human finger,” in IEEE Int. Conf. Robotics and Automation ICRA, 2008, pp. 718-724), even the user's arm is partly covered.
Disadvantages of such hand master devices are limited compatibility with arm master de-vices due to arm coverage, low comfort, fatigue, high mass and size. These drawbacks can be partly relieved by locating bulky components such as actuators externally. For instance, a hand exoskeleton, where cable transmissions are used to locate the actuators away from the hand and arm is proposed in A. Wege and A. Zimmermann, “Electromyography sensor based control for a hand exoskeleton,” in Proc. IEEE Int. Conf. Robotics and Biomimetics ROBIO, 2007, pp. 1470-1475. While such a solution can increase power density at the actuated joints, such designs are prone to suffer from mechanical losses, reduced backdrivability and backlash. Furthermore, external connections interfere with potential arm masters {to which they might be attached} or might constrain the arm workspace and mobility. Another drawback of the proposed solutions is that their use is optimized for a specific type of slave device and that the operability of the master device of varying slave devices is rather limited. Likewise, the complex and bulky constructions make it difficult to adjust the hand master device to varying operators with different hand/arm/finger sizes.
Another drawback of the proposed devices is that they are resource expensive and that the complicated mechanisms are susceptible to mechanical losses and misalignments that may lead to unnatural constraint forces and consequently uncomfortable wear and operation. The achieved device and user performance, such as the controlling accuracy, wearing comfort, etc., can therefore be low compared to the resources expended, such as material costs, complexity of required mechatronic components etc.